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P028 Role of the receptor for advanced glycation end products (RAGE) in intestinal fibrosis

S. Speca*1, M. Body-Malapel2, M. Djouina2, E. Boulanger2, A.-M. Schmidt3, P. Desreumaux2, C. Vignal2

1INSERM, U995, Lille, France, 2INSERM U995, Inflammation : mécanismes de régulation et interactions avec la nutrition et les candidose, Lille, France, 3NYU Langone Medical Center, Departments of Medicine (Endocrinology Div), Biochemistry and Molecular Pharmacology and Pathology (Pathology) , New York, United States

Background

Intestinal fibrosis is a common and severe complication of inflammatory bowel disease (IBD) characterized by excessive deposition of extracellular matrix components (ECM). Inflamed colonic mucosa of patients with active IBD shows a significant increase in expression of the receptor for advanced glycation end products (RAGE), a member of the immunoglobulin superfamily of cell surface receptors. Several evidences in kidney, liver and lung fibrosis show how the increased myofibroblast activation and the consequent ECM accumulation are regulated by RAGE.

Aim of this study is to investigate the involvement of RAGE i) in in vitro differentiation of human colonic fibroblasts (CCD-18 Co) and epithelial cells (HT29) into myofibroblasts and ii) in the development of the DSS-induced intestinal fibrosis in mice.

Methods

Differentiation of CCD-18 Co and HT29 into myofibroblasts was induced by 4 day of TGF-beta administration (1ng/mL and 10 ng/mL, respectively). Expression of alpha-SMA (ACTA2) gene and fibronectin (Fn-1) gene, as well as RAGE was measured by quantitative RT-PCR. Chronic colonic fibrosis was induced in C57BL/6 mice by successive 2,5% (w/v) DSS administration in drinking water for 6 weeks. After 6 weeks main parameters associated to a pro-fibrotic profile were assessed macroscopically (weight/length of the colon, edema, ulcers, adhesions, thickness, dilatation), histologically (inflammatory infiltrate, collagen deposition) and biologically (Tgf-beta1, Col1A1 and Fn-1 gene expression)

Results

TGF-beta-induced myofibroblast activation was associated to a significant increase in the ACTA2 expression (65%, p< 0.01 for CCD-18 Co and 183.8%, p< 0.001 for HT29) and mRNA Fn-1 levels (75.5%, p<0.001 in CCD-18 Co and 122%, p< 0.001, in HT29) and correlated with a significant RAGE upregulation both in CCD-18 Co and HT29 (48%, p<0.005 and 1.47%, p<0.005, respectively). RAGE-/- mice showed a significant 23.8% decrease of total macroscopic score and 49% decrease of total microscopic score compared to WT mice. mRNA Tgf-beta1 expression was significantly increased 3.4 fold by the DSS administration in WT mice colon, whereas it was unchanged in RAGE null mice compared to mice receiving only tap water. Col1A1 and Fn-1 genes were upregulated in DSS-treated WT mice (5.52 folds, p= 0.137 and 53 folds, p= 0.0016, respectively). Lack of RAGE decreased 3.17 folds (p= 0.0341) Col1A1 expression and totally prevents the Fn-1 upregulation induced by DSS treatment

Conclusion

The potential pro-fibrotic RAGE properties in IBD represent a new frontier for a better understanding of the mechanisms related to intestinal fibrosis and for the development of new therapeutic approaches.